Voltage regulating circuits may be encountered in virtually all kinds of electric and electronic devices. Typically, a voltage regulating circuit controls an output voltage such that the output voltage level differs as little as possible from a defined reference level. A voltage level is an instantaneous value of the voltage between two defined points or, equivalently, a momentary value of the electrical potential at a defined point or node relative to a given reference potential, for example, a ground potential. A reference level may also be referred to as a target level.
A voltage regulating circuit may comprise a feedback mechanism for controlling the output voltage level in dependence on the output voltage level. The voltage regulating circuit may, for instance, be arranged to adapt the output voltage level by iteration on the basis of the difference between the output voltage level and the reference level. However, non-iterative voltage regulating circuits also exist.
The output voltage may be applied to a consumer, such as a functional unit of an electronic circuit in order to power the consumer. The power consumption may be controlled by means of the reference voltage. For instance, a consumer powered by the output voltage may be powered on and off in dependence on whether the reference level is above or below a certain threshold. In a typical scenario, the reference voltage is set to e.g., 9 volts for powering the consumer and to, e.g., 0 volts for switching the consumer off or for setting it into an idle or sleep state.
Varying the reference level may, however, induce undesired variations in the level of the supply voltage. For instance, increasing the reference level quasi instantly from, e.g., 0 volts to, e.g., 9 volts may cause an undesired sag in the supply voltage level. Such sag or voltage drop may affect other consumers that are possibly powered by the supply voltage. Therefore, it may be beneficial to provide circuitry in which the supply voltage level is less sensitive to a consumer being switched on or off.
U.S. patent application publication number US 2010/0253314 A1 (Bitting) describes an adaptive voltage and scaling optimization optimization circuit which detects operating parameters of a core logic and generates a voltage control signal to control a reference voltage regulator.
U.S. Pat. No. 6,384,645 B2 (Brambilla and Cleris) describes an integrated circuit for producing a small slope voltage ramp.